Question 287832
Let {{{a}}} = number of correct answers
Then {{{20 - a}}} = number of incorrect answers
given:
{{{10a - 5*(20 - a) = 125}}}
{{{10a - 100 + 5a = 125}}}
{{{15a = 225}}}
{{{a = 15}}}
{{{20 - a = 5}}}
I answered 15 questions correctly
check:
{{{10a - 5*(20 - a) = 125}}}
{{{10*15 - 5*(20 - 15) = 125}}}
{{{150 - 5*5 = 125}}}
{{{150 - 25 = 125}}}
{{{125 = 125}}}
OK